Recent studies have shown that .beta.-endorphin from camel and human pituitary glands not only exhibits many of the biological properties associated with similar opiate-like peptides, but exhibits these activities to a substantially greater degree. The structural feature common to this family of peptides is an enkephalin segment corresponding to positions 1-5 of .beta.-endorphin, which constitutes a minimal requirement for elicitation of opiate-like activity. On the other hand, the "non-enkephalin" segment, i.e., residues 6-31, plays an important role in the unique actions of .beta.-endorphin.